Semi-rigid tube supporting tie

ABSTRACT

A tube supporting tie for transversely tying together two closely spaced parallel tubes having a near side and a far side. The tie comprises at least one right-hand S-shaped strap bridging the near side of the one tube and the far side of the other tube, and at least one left-hand S-shaped strap bridging the near side of the other tube and the far side of the one tube, whereby differential or transverse displacement of the tubes will primarily produce tensional stresses only. These straps are welded to the tubes. In order to minimize any mechanically induced bending stresses which may occur in the notch at the beginning of the side weld, the ends of the straps are wider than the middle portions, with these wider ends being the portions welded to the tubes.

United States Patent Freiday Apr. 29, 1975 l l SEMI-RIGID TUBE SUPPORTING TIE Primary Examiner-Kenneth W. Sprague [75] Inventor: Jay Horl Freiday, Hartford, Conn. Agemf firm-Robert Olson [73] Assignee: Combustion Engineering, Inc.,

Windsor, Connv [57] ABSTRACT A tube supporting tie for transversely tying together [22] Flled' July 1974 two closely spaced parallel tubes having a near side [2]] Appl. No.: 490,811 and a far side. The tie comprises at least one righthand S-shaped strap bridging the near side of the one tube and the far side of the other tube and at least 7' l [52] US. Cl 122/510, l. /476 one left hand p Strap g g the near Side of [5 [1 Int. Cl. F22b 37/24 the other tube and the far side of the one tube, [58] Field of Search 122/476, 478, 510;

whereby differential or transverse displacement of the 165/162 tubes Wlll primarily produce tensional stresses only. 56 R f Ct d These straps are welded to the tubes. In order to minil e erences l e mize any mechanically induced bending stresses which UNITED STATES PATENTS may occur in the notch at the beginning of the side 2,834,324 5/1958 Schocssow 122/476 weld, the ends of the straps are wider than the middle Hamilton Ct til. portions these wider ends being the portions 1196842 7/1965 Huge CILll 122/510R weldedtothetubes. 3,434.5. 3/1969 Hochmuth ct al 122/510 X 4 Claims, 3 Drawing Figures SEMI-RIGID TUBE SUPPORTING TIE BACKGROUND OF THE INVENTION The invention relates generally to fluid heaters of the tubular panel or platen type, and to the tie for transversely supporting these platens on vertical or horizontal supporting tubes. Superheater heating surface in large steam generators consists frequently of rows of suspended tubular panels or platens spaced across the upper portion of the furnace chamber, with these platens often constructed of vertical, closely spaced parallel tubes. The platens are supported from hanger tubes which are integral parts of the platen and extend through the roof of the furnace to headers which are supported from overhead steel. Being of considerable length and exposed to high velocity gas streams, these platens are exposed to vibration and swaying, subjecting the welded connection of the tie uniting the main body of the platen with the hanger tubes to considerable bending and torsional stresses. Because these stresses occur in an atmosphere of high temperature, present tie supports often fail causing frequent and costly shutdown of the steam generator. One form of tie presently used is that disclosed in US. Pat. No. 3,434,531 which issued on Mar. 25, 1969. This patent discloses the use of S-shaped ties' for securing parallel tubes together. The present invention is directed to an improved arrangement of the tube supporting ties disclosed in the above-mentioned patent.

SUMMARY OF THE INVENTION The invention is directed to a tube supporting tie for tying two closely spaced parallel tubes together, the tubes having a near side and a far side, the tube supporting tie including a right-hand S-shaped strap passing between the tubes and shaped to conform to the contour of the tubes, and structurally connecting the near side of one tube with the far side of the other tube, and a left-hand S-shaped strap passing between the tubes and shaped to conform to the contour of the tubes and structurally connecting the far side of said one tube with the near side of the other tube, with the ends of both straps being wider than the middle portions of the straps, such widened ends being welded to the tubes. The ends of each strap have rounded corners, so that the welding thereof to the tube can be accomplished more readily, and can be accomplished in a single welding pass.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side view of the upper portion of a steam generator having platen superheaters which are tied together in accordance with the invention;

FIG. 2 is an enlarged elevational view of the tubes and the apparatus for tying the tubes together; and

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now to FIG. 1, numeral designates the upper portion of a furnace. An upper drum 12 has a plurality of steam generating tubes 14 extending downwardly therefrom, in which water is heated to steam. Steam generated in tubes 14 is separated from the water within the drum 12, with the steam passing over into superheater inlet header 16. The steam passes downwardly from header 16 through a plurality of hanger tubes 18, 20, 22 and 24. These tubes extend downwardly into the furnace or combustion chamber a substantial distance, before bending or looping back in an upward direction. The serpentine, inter-nested relationship of the tubes 18, 20, 22 and 24 form a superheater panel or platen. After making a number of loops within the furnace, the tubes exit from the furnace and are tied at their outer ends to superheater outlet header 26. From this header, the steam flows on to another superheater panel or platen, which is similar in construction to the panel shown.

The superheater platen is made up of a number of inter-nested serpentine tubes, and is subjected to high velocity combustion gases flowing thereacross. In addition, the panel is occasionally cleaned by means of retractable soot blowers to remove slag deposits therefrom. These high velocity flows across the tube bank can cause vibration and swaying problems.

In order to minimize relative movement between the tubes, the first hanger tubes are welded together by means of welds 25. The internested tubes within the panel are also welded together by means of welds 25. The inner hanger tube 24 is connected to the first loop of the tubular panel by means of a support tie 28. The same type of support tie is used at the other side of the tubular panel where the tubes exit from the furnace.

The improved tie support is shown in more detail in FIGS. 2 and 3. As can be seen in these figures, vertical tube lengths 24 and 24 are tied together by means of a plurality of S-shaped straps 26 and 28. The straps 26 are right-hand S-shaped straps, the numerals 28 designate left-hand S-shaped straps. Thes straps are alternated, as you move vertically downwardly, with the uppermost strap being a right-hand strap, the next lower one being a left-hand strap, and so forth. Such a support arrangement offers a semi-rigid connection which upon swaying of the tubular panels is subject to tension and only minor bending and shear stresses. The construction of S-shaped straps for supporting a tubular panel is shown in previously mentioned US. Pat. No. 3,434,531.

The ends of the straps shown in FIGS. 2 and 3 are widened or enlarged, with these widened portions 30 being welded at 32 to their respective tubes. In order to permit easy welding, the corners 34, 36 are rounded, so that one end of the strap can be welded in a single welding pass. The widened or enlarged ends of the straps which are welded to the tubes serve to provide a number of advantages. It provides a definite stopping point for the side welds which are manually made in the shop, which are difficult to accurately control lengthwise. As can be seen in FIGS. 2 and 3, the weld stops at a point which leaves at least of unwelded strap surrounding each tube. Thus any tendency of the tubes 24' and 24 to move away from each other will not put cracking stresses on the weld. The widened ends also reduce any mechanically induced bending stresses which may occur in the notch at the beginning of the side weld by moving the lines of force away from the notch. Such stresses can occur during the compression cycle when the adjacent strap is in tension. Because of the impossibility of obtaining perfect wrap-around of the straps to the tubes, there may be a small amount of movement within the assembly. This can be dissipated through the curved section of the weld.

The enlarged welded ends also tend to reduce any temperature induced stress at the weak weld points by reducing the incremental temperature differences between the wide portion of the strap and the superheater tube since there will be less heat flowing from the narrower portion of the strap into the wider portion than there would be through a constant width strap. Because the welded portion is in more intimate contact with the tube, it is kept somewhat cooler.

What is claimed is:

1. In combination a tube supporting tie for tying two closely spaced parallel tubes together, said tubes having a near side and a far side, the tube supporting tie including a right-hand S-shaped strap passing between the tubes and shaped to conform to the contour of the tubes, and structurally connecting the near side of one tube with the far side of the other tube, and a left-hand S-shaped strap passing between the tubes and shaped to conform to the contour of the tubes and structurally connecting the far side of said one tube with the near side of the other tube, the ends of both straps being wider than the middle portions of the straps, with the widened ends welded to the tubes.

2. The combination set forth in claim 1, wherein the unwelded portion of each strap encompasses at least a arc of each tube.

3. The combination set forth in claim 1, wherein the ends of each strap have rounded corners, and the weld of each end extends along the entire end edge, and around .each of the adjacent corners.

4. The combination set forth in claim 1, wherein there is more than one right-hand S-shaped strap, and

more than one left-hand S-shaped strap. 

1. In combination a tube supporting tie for tying two closely spaced parallel tubes together, said tubes having a near side and a far side, the tube supporting tie including a right-hand Sshaped strap passing between the tubes and shaped to conform to the contour of the tubes, and structurally connecting the near side of one tube with the far side of the other tube, and a lefthand S-shaped strap passing between the tubes and shaped to conform to the contour of the tubes and structurally connecting the far side of said one tube with the near side of the other tube, the ends of both straps being wider than the middle portions of the straps, with the widened ends welded to the tubes.
 2. The combination set forth in claim 1, wherein the unwelded portion of each strap encompasses at least a 90* arc of each tube.
 3. The combination set forth in claim 1, wherein the ends of each strap have rounded corners, and the weld of each end extends along the entire end edge, and around each of the adjacent corners.
 4. The combination set forth in claim 1, wherein there is more than one right-hand S-shaped strap, and more than one left-hand S-shaped strap. 